The present invention relates generally to automotive airbag doors which are intended to be concealed from the view of a vehicle occupant prior to deployment.
It is known to manufacture automotive instrument panels containing airbag doors which are concealed from the view of a vehicle occupant prior to deployment. Such concealed airbag doors are often characterized by the non-existence of any definitive seam, styling line, gap, or similar feature between the airbag door and instrument panel outer surfaces which would indicate the airbag door""s presence. An example of such a structure is described in U.S. Pat. No. 5,810,388. The ""388 Patent describes a method of manufacturing an automotive instrument panel that conceals an airbag door. The steps of manufacturing the instrument panel include providing a molded substrate having first and second surfaces and an aperture therethough, and a metal door having a generally U-shaped slot secured to the second surface of the substrate with a plurality of attaching posts. The slot has first and second ends being spaced apart a distance greater than the length of the aperture. The slot defines a flap in the door. The flap has a width greater than the width of the aperture. The door and substrate assembly is placed within a mold tool and a pre-molded covering is juxtaposed the substrate. A quantity of foam is injected between the substrate and covering and secures the covering to the substrate.
Recently, certain automobile manufactures have implemented airbag door test criteria limiting the amount of fragmentation upon deployment. Fragmentation generally refers to those portions of the airbag door, instrument panel or their surrounding structures which may become separated from their respective components upon airbag deployment and subsequently enter into the vehicle occupant compartment, possibly at the risk of injury to a vehicle occupant. More specifically, some automobile manufactures have sought to limit the possibility of foam fragmentation occurring upon airbag deployment. The ""388 Patent does not provide a structure for reduced levels of foam fragmentation or a method for such.
In addition, it has become desirable to develop airbag doors with increased stiffness in order to reduce airbag door bending and distortion during deployment and, more particularly, the associated deployment force and energy losses occuring with such bending and distortion. Such increases in airbag door stiffness result in increased transmission efficiency of airbag deployment forces in separating the airbag door from its trim member, in this case an instrument panel. More particularly, airbag doors with increased stiffness tend to deploy in a more uniform and efficient manner given better transmission of deployment forces in a more even array. While the ""388 Patent provides for some increased stiffness of the airbag door by virtue of indentations of the metal door, it has been found that additional stiffness and resistance to bending is preferred in certain instances. This has been particularly evident with the use of so called xe2x80x9csecond generationxe2x80x9d, xe2x80x9cdepoweredxe2x80x9d or xe2x80x9cdual stagexe2x80x9d airbag systems. Such systems are designed to emit lower energy levels and associated deployment forces upon the detection of an out-of-position vehicle occupant than the previous first generation systems. In such an instance, it has been found that airbag doors with increased stiffness and transmission efficiency of deployment forces are desired for better operation of the airbag system and, more particularly, separation of the airbag door from its trim member with reduced fragmentation.
In addition, it has become desirable to develop trim member substrates and, in particular, instrument panel substrates with a reduced possibility of fragmentation occuring, but still using the same low cost materials. It has been found that fragmentation from the instrument panel substrate is more apt to occur closer to the airbag door area than from other areas of the instrument panel. The ""388 Patent does not provide a structure for reduced levels of such substrate fragmentation or a method for such.
Accordingly, the present invention provides a structure and method to provide an improved airbag door system for reduced levels of foam and substrate fragmentation.
According to one feature of the invention, an airbag door system is provided comprising a substrate, an outer shell and a foam where all three layers possess a line of mechanical weakness with each line of mechanical weakness at least partially separating each layer into an airbag door portion and a trim member portion.
According to another feature of the invention, a substrate line of mechanical weakness comprises at least one substrate aperture.
According to another feature of the invention, an outer shell line of mechanical weakness comprises an outer shell reduced thickness portion defined by an outer shell sever extending partially through an outer shell thickness from an outer shell lower surface towards an outer shell upper surface.
According to another feature of the invention, a foam line of mechanical weakness comprises a foam reduced thickness portion defined by a foam sever extending partially through a foam thickness from a foam lower surface towards a foam upper surface.
According to another feature of the invention, an outer shell line of mechanical weakness is displaced relative to a foam line of mechanical weakness.
According to another feature of the invention, an outer shell line of mechanical weakness is displaced relative to a substrate line of mechanical weakness.
According to another feature of the invention, an outer shell sever at the outer shell lower surface is in direct contact with a foam upper surface.
According to another feature of the invention, an outer shell sever comprises first and second outer shell sever surfaces where the outer shell sever is sufficiently narrow such that at least a portion of the first and second outer shell sever surfaces are in direct contact with one another after the outer shell sever is formed.
According to another feature of the invention, an outer shell sever comprises first and second outer shell sever surfaces where the outer shell sever is sufficiently narrow such that at least a portion of the first and second outer shell sever surfaces are in direct contact with one another after a foam is formed.
According to another feature of the invention, an outer shell sever comprises first and second outer shell sever surfaces where the outer shell sever is sufficiently narrow such that a foam is not in direct contact with at least a portion of either the first or second outer shell sever surfaces.
According to another feature of the invention, an outer shell sever comprises first and second outer shell sever surfaces where the outer shell sever is sufficiently narrow such that a foam does not occupy at least a portion of the outer shell sever.
According to another feature of the invention, an outer shell sever is continuous or discontinuous.
According to another feature of the invention, a discontinuous outer shell sever comprises a plurality of holes, which may further comprise through holes or blind holes.
According to another feature of the invention, an outer shell sever is perpendicular or other than perpendicular to an outer shell lower surface.
According to another feature of the invention, an outer shell sever comprises an outer shell sever depth between 5% and 95% of an outer shell thickness.
According to another feature of the invention, an outer shell reduced thickness portion is between 5% and 95% of an outer shell thickness.
According to another feature of the invention, a foam sever comprises first and second foam sever surfaces where the foam sever is sufficiently narrow such that at least a portion of the first and second foam sever surfaces are in direct contact with one another after the foam sever is formed.
According to another feature of the invention, a foam sever is continuous or discontinuous.
According to another feature of the invention, a discontinuous foam sever comprises a plurality of slots.
According to another feature of the invention, a foam sever is perpendicular or other than perpendicular to a foam lower surface.
According to another feature of the invention, a foam sever comprises a foam sever depth between 12.5% and 96.7% of a foam thickness.
According to another feature of the invention, a foam reduced thickness potion is between 3.3% and 87.5% of a foam thickness.
According to another feature of the invention, a substrate aperture is elongated.
According to another feature of the invention, a substrate aperture comprises a substrate aperture length and a substrate aperture width where the substrate aperture length is greater than the substrate aperture width.
According to another feature of the invention, a substrate aperture comprises a substrate aperture length and a substrate aperture width where the substrate aperture length is greater than or equal to four times the substrate aperture width.
According to another feature of the invention, a substrate aperture comprises a rectangle shape, an oval shape, a hexagon shape or a trapezoid shape.
According to another feature of the invention, a substrate aperture terminates in a tear stop.
According to another feature of the invention, an airbag door substrate portion and trim member substrate portion are linked by at least one substrate bridge.
According to another feature of the invention, a substrate bridge is formed at the same time and from the same material as an airbag door substrate portion or a trim member substrate portion.
According to another feature of the invention, a substrate bridge reduces independent movement of an airbag door substrate portion relative to a trim member substrate portion prior to an airbag deployment.
According to another feature of the invention, a substrate bridge breaks during an airbag deployment to permit an airbag door substrate portion to move independent of a trim member substrate portion.
According to another feature of the invention, a substrate bridge comprises a substrate bridge width where the substrate bridge width is equal to or greater than a substrate aperture width.
According to another feature of the invention, a substrate bridge comprises a substrate bridge length where the substrate bridge length is no greater than 10.0 mm.
According to another feature of the invention, a substrate bridge comprises a substrate bridge cross-sectional thickness and a substrate bridge width where the substrate bridge cross-sectional thickness across the substrate bridge width is constant.
According to another feature of the invention, a substrate bridge comprises a substrate bridge cross-sectional thickness and a substrate bridge width where the substrate bridge cross-sectional thickness across the substrate bridge width is variable.
According to another feature of the invention, a substrate bridge comprises a substrate bridge cross-sectional thickness and a substrate bridge width where the substrate bridge cross-sectional thickness across the substrate bridge width is equal to or less than a substrate thickness of an airbag door substrate portion or a trim member substrate portion.
According to another feature of the invention, a substrate bridge comprises a substrate bridge edge appearance where the substrate bridge edge appearance is U-shaped, V-shaped, or off-centered V-shaped.
According to another feature of the invention, an airbag door system further comprises a reinforcement member possessing a line of mechanical weakness at least partially separating the reinforcement member into an airbag door reinforcement member portion and trim member reinforcement member portion.
According to another feature of the invention, a reinforcement member line of mechanical weakness comprises at least one reinforcement member aperture.
According to another feature of the invention, at least a portion of an airbag door reinforcement member portion overlies at least a portion of an airbag door substrate portion to create a double material layer comprising a stiffness greater than the airbag door reinforcement member portion or the airbag door substrate portion individually.
According to another feature of the invention, at least a portion of a reinforcement member aperture and at least a portion of a substrate aperture overlie.
According to another feature of the invention, at least a portion of a trim member reinforcement member portion overlies at least a portion of a trim member substrate portion to an edge of said trim member substrate portion adjacent said substrate aperture.
According to another feature of the invention, the trim member reinforcement member portion comprises a ring.
According to another feature of the invention, the trim member reinforcement member portion comprises a closed ring.
According to another feature of the invention, at least a portion of a reinforcement member lower surface and a substrate upper surface are separated by tape.
According to another feature of the invention, at least a portion of a reinforcement member lower surface and a substrate upper surface are separated by a polymer film.
According to another feature of the invention, a polymer film further comprises two surfaces and an adhesive applied to both of the surfaces where the adhesive bonds a reinforcement member lower surface to a substrate upper surface.
According to another feature of the invention, at least a portion of said reinforcement member lower surface and said substrate upper surface are adhesively bonded.
According to another feature of the invention an airbag door system further comprises an airbag canister housing.
According to another feature of the invention, at least a portion of the airbag canister housing upper surface and the substrate lower surface are adhesively bonded.